This PR deprecates `<ccomplex>`, `<cstdbool>`, `<ctgmath>`, and
`<ciso646>` in C++17 and "removes" them in C++20 by special deprecation
warnings.
`<cstdalign>` is previously missing. This PR also tries to add them, and
then deprecates and "removes" `<cstdalign>`.
Papers:
- https://wg21.link/P0063R3
- https://wg21.link/P0619R4Closes#99985.
---------
Co-authored-by: Louis Dionne <ldionne.2@gmail.com>
In C++20 mode, `__cpp_lib_optional` and `__cpp_lib_variant` should be
`202106L` due to DR P2231R1.
In C++26 mode, `__cpp_lib_variant` should be bumped to `202306L` due to
P2637R3.
- Clang 16/17 shouldn't get this bumping (as member `visit` requires
explicit object parameters), but it's very tricky to make the bumping
conditionally enabled. I _hope_ unconditionally bumping in C++26 will be
OK for LLVM 20 when the support for Clang 17 is dropped.
Related PRs:
- https://reviews.llvm.org/D102119
- #83335
- #76447
Only the [cmp.alg] part (for `comparison_meow_fallback` CPOs) in the
paper required changes. Other parts merely fixed preconditions of some
standard library functions.
I strongly feel that P2167R3 should be a DR despite that it is not a DR
officially: CPOs -> C++20; remain parts -> C++98/11 (except that
_`boolean-testable`_ should be transformed into the original
_BooleanTestable_ requirements in the old resolution of LWG2114).
Note that P2167R3 damaged the resolution of LWG3465: the type of `F < E`
was left underconstrained. I've tried to submit an LWG issue for this,
which is now LWG4157.
Drive-by change:
- enable some test coverages in `compare_strong_order_fallback.pass.cpp`
when `TEST_LONG_DOUBLE_IS_DOUBLE`, following up #106742Closes#105241.
This patch adds a large number of missing includes in the libc++ headers
and the test suite. Those were found as part of the effort to move
towards a mostly monolithic top-level std module.
We waited before supporting std::jthread fully because we wanted to
investigate other implementation strategies (in particular one involving
std::mutex). Since then, we did some benchmarking and decided that we
wouldn't be moving forward with std::mutex. Hence, there is no real
reason to punt on making std::jthread & friends non-experimental.
This patch implements https://wg21.link/P2747R2.
The library changes affect direct `operator new` and `operator new[]`
calls even when the core language changes are absent.
The changes are not available for MS ABI because the `operator new` and
`operator new[]` are from VCRuntime's `<vcruntime_new.h>`. A feature
request was submitted for that [1].
As a drive-by change, the patch reformatted the whole `new.pass.cpp` and
`new_array.pass.cpp` tests.
Closes#105427
[1]: https://developercommunity.visualstudio.com/t/constexpr-for-placement-operator-newope/10730304.
This patch implements https://wg21.link/p2609r3.
The test code was originally authored by JMazurkiewicz.
Notes:
- P2609R3 is not officially a Defect Report, but MSVC STL
implements it in C++20 mode.
Moreover, P2609R3 and P2997R1 touch exactly the same set of
concepts, and MSVC STL and libc++ have already treated P2997R1
as a DR.
- This patch also adjusted feature-test macros.
+ In C++20 mode, the value of __cpp_lib_ranges should be `202110L` because
- `202202L` covers `range_adaptor_closure` (P2387R3), and
- `202207L` covers move-only types in range adaptors (P2494R2).
And all of these changes are only available since C++23 mode.
+ In C++23 mode, the value should be `202406L` because
- `202211L` covers removing poison overloads (P2602R2),
- `202302L` covers relaxing projected value types (P2609R3), and
- `202406L` covers removing requirements on `iter_common_reference_t` (P2997R1).
And all of these changes are already or being implemented.
Fixes#105253.
Co-authored-by: Jakub Mazurkiewicz <mazkuba3@gmail.com>
Works towards P0619R4/#99985.
- std::uncaught_exception was not previously deprecated. This patch
deprecates it since C++17 as per N4259. std::uncaught_exceptions is
used instead as libc++ unconditionally provides this function.
- _LIBCPP_ENABLE_CXX20_REMOVED_UNCAUGHT_EXCEPTION restores
std::uncaught_exception.
- As a drive-by, this patch updates the C++20 status page to
explain that D.11 is already done, since it was done in
578d09c1b1.
This trait is implemented in C++26 conditionally on the compiler
supporting the __builtin_is_virtual_base_of intrinsic. I believe only
tip-of-trunk Clang currently implements that builtin.
Closes#105432
Issue #43670 describes a situation where the following comparison will
issue a warning when -Wzero-as-null-pointer-constant is enabled:
#include <compare>
auto b = (1 <=> 2) < 0;
This code uses operator<(strong_ordering, Unspecified), which is
specified by the Standard to only work with a literal 0. In the library,
this is achieved by constructing Unspecified from a pointer, which works
but has the downside of triggering the warning.
This patch uses an alternative implementation where we require that the
operator is used exactly with an int of value 0 (known at compile-time),
however that value can technically be an expression like `1 - 1`, which
makes us a bit less strict than what's specified in the Standard.
Fixes#43670
Implements [P1223R5][] completely.
Includes an implementation of `find_last`, `find_last_if`, and
`find_last_if_not`.
[P1223R5]: https://wg21.link/p1223r5
The sized deallocation test cases fail on AIX, z/OS, and MinGW because
they default to `-fno-sized-deallocation`. This patch XFAILs these test
cases for the affected targets. Once they change the default, we will
get `unexpectedly pass`.
This patch implements P2389R2, which was adopted at the St. Louis meeting.
It builds upon previous enhancements from P2299R3, which introduced deduction
guides and the `dextents` alias template.
In order to define the format __cpp_lib_format to its initial value
(201907) these papers need to be completed:
- P0645R10 Text Formatting
- P1652R1 Printf corner cases in std::format
- 1361R2 Integration of chrono with text formatting The first two have
been implemented for a while the latter is almost done.
The next value (202106) requires:
- P2216R3 std::format improvements which has been implemented
The next value (202110) requires:
- P2418R2 Add support for std::generator-like types to std::format
- P2372R3 Fixing locale handling in chrono formatters The first one has
been implemented for a while the latter is almost done. The latter paper
is a DR against 1361R2 and both are implemented at the same time.
We've had user feedback that the missing of the __cpp_lib_format makes
their lives harder (https://github.com/llvm/llvm-project/issues/77773).
The missing papers 1361R2 and P2372R3 are very close to completion and
might completed before LLVM-19, but it will be a close call. This has
been discussed in the monthly libc++ meeting and we decided to set the
__cpp_lib_format so it will be set in LLVM-19.
Based on the discussion and the implementation status the
__cpp_lib_format is set to 202110.
Fixes#77773
Clang 19 turned on sized deallocation *by default*, but older versions
of Clang did support sized deallocation nonetheless. This updates a few
comments and removes UNSUPPORTED annotations that shouldn't be needed in
a test that passes -fsized-deallocation directly.
In #90373 size deallocation was enabled by default. Some test were
disabled to propagate the clang changes to the libc++ CI. These changes
have been propagated so the test filter can be updated.
Fixes#54470.
See https://eel.is/c++draft/global.functions#2:
> A call to a non-member function signature described in [support]
> through [thread] and [depr] shall behave as if the implementation
> declared no additional non-member function signatures.
and https://eel.is/c++draft/global.functions#3:
> An implementation shall not declare a non-member function signature
> with additional default arguments.
This patch removes many annotations that are not relevant anymore since
we don't support or test back-deploying to macOS < 10.13. It also cleans
up raw usage of target triples to identify versions of dylibs shipped on
prior versions of macOS, and uses the target-agnostic Lit features
instead. Finally, it reorders both the Lit backdeployment features and
the corresponding availability macros in the library in a way that makes
more sense, and reformulates the Lit backdeployment features in terms of
when a version of LLVM was introduced instead of encoding the system
versions on which it hasn't been introduced yet. Although one can be
derived from the other, encoding the negative form is extremely
error-prone.
Fixes#80901
We were not making any distinction between e.g. the "Apple-flavored"
libc++ built from trunk and the system-provided standard library on
Apple platforms. For example, any test that would be XFAILed on a
back-deployment target would unexpectedly pass when run on that
deployment target against the tip of trunk Apple-flavored libc++. In
reality, that test would be expected to pass because we're running
against the latest libc++, even if it is Apple-flavored.
To solve this issue, we introduce a new feature that describes whether
the Standard Library in use is the one provided by the system by
default, and that notion is different from the underlying standard
library flavor. We also refactor the existing Lit features to make a
distinction between availability markup and the library we're running
against at runtime, which otherwise limit the flexibility of what we can
express in the test suite. Finally, we refactor some of the
back-deployment versions that were incorrect (such as thinking that LLVM
10 was introduced in macOS 11, when in reality macOS 11 was synced with
LLVM 11).
Fixes#82107
The feature has been implemented in LLVM 18 as an experimental feature.
This marks the paper as complete and sets the feature-test macro.
Implements
- P2465R3 Standard Library Modules std and std.compat
Fixes: https://github.com/llvm/llvm-project/issues/89579
The paper
P0768R1 Library Support for the Spaceship (Comparison) Operator
did not add a feature-test macro. This omission has been corrected in
P1353R0 Missing Feature Test Macros
This enables the FTM for P0768R1
Fixes: https://github.com/llvm/llvm-project/issues/73953
---------
Co-authored-by: S. B. Tam <cpplearner@outlook.com>
[P2845R8](https://wg21.link/P2845R8) "Formatting of
`std::filesystem::path`" and [P2587R3](https://wg21.link/P2587R3)
"`to_string` or not `to_string`" are C++26 features, so they should be
marked accordingly in `generate_feature_test_macro_components.py`.
I verified that without my changes, running the script produced no
edits. Then with my changes, I ran the script to regenerate all files,
with no other manual edits.
Found while running libc++'s tests with MSVC's STL, which noticed this
because it's currently a C++23-only implementation.
Note that @H-G-Hristov has a draft implementation of P2587R3: #78100
Since C++14 has been released for about nine years and most standard
libraries have implemented sized deallocation functions, it's time to
make this feature default again.
This is another try of https://reviews.llvm.org/D112921.
The original commit cf5a8b4 was reverted by 2e5035a due to some
failures (see #83774).
Fixes#60061
These macros are used by STL implementations to support implementation
of std::hardware_destructive_interference_size and
std::hardware_constructive_interference_size
Fixes#60174
---------
Co-authored-by: Louis Dionne <ldionne.2@gmail.com>
Since C++14 has been released for about nine years and most standard
libraries have implemented sized deallocation functions, it's time to
make this feature default again.
This is another try of https://reviews.llvm.org/D112921.
Fixes#60061
We noticed that some feature-test macros were not conditional on
configuration flags like _LIBCPP_HAS_NO_FILESYSTEM. As a result, code
attempting to use FTMs would not work as intended.
This patch adds conditionals for a few feature-test macros, but more
issues may exist.
rdar://122020466
In D144319, Clang tried to land a change that would cause some functions
that are not supposed to return nullptr to optimize better. As reported
in https://reviews.llvm.org/D144319#4203982, libc++ started seeing
failures in its CI shortly after this change was landed.
As explained in D146379, the reason for these failures is that libc++'s
throwing `operator new` can in fact return nullptr when compiled with
exceptions disabled. However, this contradicts the Standard, which
clearly says that the throwing version of `operator new(size_t)` should
never return nullptr. This is actually a long standing issue. I've
previously seen a case where LTO would optimize incorrectly based on the
assumption that `operator new` doesn't return nullptr, an assumption
that was violated in that case because libc++.dylib was compiled with
-fno-exceptions.
Unfortunately, fixing this is kind of tricky. The Standard has a few
requirements for the allocation functions, some of which are impossible
to satisfy under -fno-exceptions:
1. `operator new(size_t)` must never return nullptr
2. `operator new(size_t, nothrow_t)` must call the throwing version and
return nullptr on failure to allocate
3. We can't throw exceptions when compiled with -fno-exceptions
In the case where exceptions are enabled, things work nicely.
`new(size_t)` throws and `new(size_t, nothrow_t)` uses a try-catch to
return nullptr. However, when compiling the library with
-fno-exceptions, we can't throw an exception from `new(size_t)`, and we
can't catch anything from `new(size_t, nothrow_t)`. The only thing we
can do from `new(size_t)` is actually abort the program, which does not
make it possible for `new(size_t, nothrow_t)` to catch something and
return nullptr.
This patch makes the following changes:
1. When compiled with -fno-exceptions, the throwing version of `operator
new` will now abort on failure instead of returning nullptr on failure.
This resolves the issue that the compiler could mis-compile based on the
assumption that nullptr is never returned. This constitutes an API and
ABI breaking change for folks compiling the library with -fno-exceptions
(which is not the general public, who merely uses libc++ headers but use
a shared library that has already been compiled). This should mostly
impact vendors and other folks who compile libc++.dylib themselves.
2. When the library is compiled with -fexceptions, the nothrow version
of `operator new` has no change. When the library is compiled with
-fno-exceptions, the nothrow version of `operator new` will now check
whether the throwing version of `operator new` has been overridden. If
it has not been overridden, then it will use an implementation
equivalent to that of the throwing `operator new`, except it will return
nullptr on failure to allocate (instead of terminating). However, if the
throwing `operator new` has been overridden, it is now an error NOT to
also override the nothrow `operator new`. Indeed, there is no way for us
to implement a valid nothrow `operator new` without knowing the exact
implementation of the throwing version.
In summary, this change will impact people who fall into the following
intersection of conditions:
- They use the libc++ shared/static library built with `-fno-exceptions`
- They do not override `operator new(..., std::nothrow_t)`
- They override `operator new(...)` (the throwing version)
- They use `operator new(..., std::nothrow_t)`
We believe this represents a small number of people.
Fixes#60129
rdar://103958777
Differential Revision: https://reviews.llvm.org/D150610
